Kinetic modelling of the catalytic conversion of synthesis gas

A kinetic study for the one-step conversion of synthesis gas to gasoline on a ZnO–Cr₂O₃–ZSM-5 catalyst is described. On this catalyst, three reactions are involved in the overall transformation of synthesis gas: the methanol synthesis, the conversion of methanol to hydrocarbons and the water–gas shift reaction. Under the operating conditions selected for the study, it was found that the water–gas shift was at equilibrium and the methanol was completely converted to hydrocarbons. Consequently, it was postulated that the kinetics of the limiting reaction step, the methanol synthesis on the ZnO–Cr₂O₃ component, was the one that controls the overall reaction rate. Three kinetic model equations describing the rate of synthesis gas conversion on the bifunctional catalyst, were considered to fit the data of the experimental runs performed in a Berty well-mixed reactor. Those equations were derived under very special conditions where the methanol decomposition term could be neglected. It was also observed that in the kinetic equations a term involving the fugacity of CO₂ was required to predict the rate properly. The catalyst deactivation was also taken into account in the analysis.     

Reaction Kinetics and Coking Behavior for Furan Deoxygenation via Catalytic Pyrolysis Using Methane

The effective deoxygenation of oxygenates remains a major challenge that needs to be overcome for industrial‐scale conversion of biomass to fuels. Present technology uses expensive gaseous hydrogen for deoxygenation. This work looks at the possibility of using methane or natural gas as an alternative for the deoxygenation process. Catalytic pyrolysis studies were carried out using furan as the model oxygenate in the presence of methane in a fixed‐bed reactor over 5 % Ni/HZSM‐5 as catalyst. The effects of temperature and space velocity on the catalyst activity, reaction kinetics, and deactivation behavior were studied. It was found that the deoxygenation of furan was first and second order with respect to furan and methane concentration, respectively. Deactivation studies suggested that catalyst deactivation takes place through poisoning, fouling, and sintering.     

Catalytic combustion kinetics of isopropanol over novel porous microfibrous‐structured ZSM‐5 coating/PSSF catalyst

Porous thin‐sheet cobalt–copper–manganese mixed oxides modified microfibrous‐structured ZSM‐5 coating/PSSF catalysts were developed by the papermaking/sintering process, secondary growth process, and incipient wetness impregnating method. Paper‐like sintered stainless steel fibers (PSSF) support with sinter‐locked three‐dimensional networks was built by the papermaking/sintering process, and ZSM‐5 coatings were fabricated on the surface of stainless steel fibers by the secondary growth process. Catalytic combustion performances of isopropanol at different concentrations over the microfibrous‐structured Co–Cu–Mn (1:1:1)/ZSM‐5 coating/PSSF catalysts were measured to obtain kinetics data. The catalytic combustion kinetics was investigated using power–rate law model and Mars–Van Krevelen model. It was found that the Mars–Van Krevelen model provided fairly good fits to the kinetic data. The catalytic combustion reaction occurred by interaction between isopropanol molecule and oxygen‐rich centers of modified microfibrous‐structured ZSM‐5 coating/PSSF catalyst. The reaction activation energies for the reduction and oxidation steps are 60.3 and 57.19 kJ/mol, respectively. © 2014 American Institute of Chemical Engineers AIChE J, 61: 620–630, 2015     

烷烃在ZSM-5分子筛上吸附扩散的气相色谱研究

利用气相色谱法测定了不同色谱柱温度和不同载气流速下,C1~12烷烃在ZSM-5分子筛上的保留时间,并利用相关公式对测试结果进行了线性回归分析,测得了吸附热力学参数和扩散系数;考察了色谱柱温度、烷烃碳链长度和载气流速对烷烃在ZSM-5分子筛上吸附扩散的影响。实验结果表明,回归分析的线性相关性良好,色谱柱温度越高,孔道对吸附质的吸附能力越弱;在不同载气流速下,轴向扩散系数不同;随烷烃碳链长度的增加,吸附焓变呈先增大后减小的趋势,轴向扩散系数呈线性增长;C1~12烷烃在ZSM-5分子筛上的吸附焓变在-1.264~-42.975 k J/mol之间;当载气流速为2.654~4.246 cm/s时,C1~4烷烃的轴向扩散系数在0.328 8~0.551 7 cm2/s之间;当载气流速为5.308~13.270 cm/s时,C1~4烷烃的轴向扩散系数在0.430 2~1.456 4 cm2/s之间。     

FCC催化剂新型载体的探索——皂石基复合材料

FCC催化剂的改性主要集中于载体和活性组分,本文旨在合成一种新型复合层柱载体即皂石与微孔分子筛复合结构以改善层柱粘土为载体时稳定性方面的问题。实验结果表明晶化温度为120℃时较适宜;随晶化时间的增长,复合材料的层间距逐渐增大;酸量的变化会影响进入层间的ZSM-5的结构单元的聚集。复合材料的热稳定性和水热稳定性都较皂石有所改善,在催化裂化领域具有较好的应用前景。     

Synthesis of modified catalyst and stabilization of CuO/NH4‐ZSM‐5 for conversion of methanol to gasoline

In this article, the catalytic conversion of methanol to gasoline range hydrocarbons has been studied over CuO/ NH₄‐ZSM‐5(3,5,7,9%) catalysts prepared via sono‐chemistry methods. In order to improve, copper oxide can be used as a booster on NH₄‐ZSM‐5 this catalyst property. Accordingly, the conversion process of Methanol to Gasoline (MTG) was conducted under a pressure of 1 atm and temperature of 400°C by a fixed‐bed reactor on copper oxide catalysts which were prepared based on synthetic NH₄‐ZSM‐5. The synthetic catalyst was investigated by such analyses as BET, XRD, FT‐IR, and SEM. Formation of copper oxide phase and proper distribution of copper oxide were proven on the basic level of using XRD analysis. BET analysis showed the reduction in catalyst level and SEM images depicted the proper distribution of particles. The present investigation is to study the effect of CuO loading on NH4‐ZSM‐5 support for conversion of methanol to gasoline range hydrocarbons. A series of CuO/ NH4‐ZSM‐5 catalysts were prepared, characterized, and experimented for their performance on methanol conversion and hydrocarbon yield.     

甲醇制烯烃催化剂研究进展

综述了甲醇制烯烃催化剂的研究进展,从晶体结构、改性方法、催化性能等方面分析了两种重要的甲醇制烯烃催化剂ZSM-5和SAPO-34;并介绍了由上述分子筛开发出的ZSM-5/磷酸铝复合分子筛。     

纳米ZSM-5分子筛受限空间合成

采用中孔碳纳料管为惰性基体,通过限定空间尺寸法合成n(SiO2)/n(Al2O3)=100,平均晶粒度为27nm的纳米ZSM-5分子筛。合成产物分别采用X射线粉末衍射(XRD)、红外光谱(IR)、透射电镜(TEM)、扫描电镜(SEM)进行表征,并对水解时间、碳源等影响因素进行了研究。结果表明,合成的分子筛具有典型的ZSM-5骨架结构和纳米尺寸,并且由于小尺寸效应该样品呈球形聚集态。采用碳纳米管的纯化方法,较长的水解时间、合适的中孔碳源和铝源均有利于纳米分子筛的合成。